There are many solutions for capturing 3D images including stereo camera, time-of-flight, and structure light. In the solution using structure light, a periodical pattern is generated as structure light. The periodical pattern may comprise periodical lines such as 1D or 2D grid. It may also comprise 1D or 2D periodical pattern of dots. The structure light is projected on a target surface, and the structure light on the target surface is captured by a camera. If the target surface is flat, the captured structure light is not distorted. If the target surface is not flat, the topographical structure of the target surface will distort the projected structure light. The topographical structure of the target surface can be retrieved from the captured distorted structure light. In this manner, structure light may be used for 3D imaging.
The structure light may be IR light or visible light. An IR camera may be used for capturing the IR structure light on the target surface, and a visible camera may be used for capturing the visible structure light on the target surface.
The stereo camera solution needs a sufficient parallax, which in turn needs a relatively large base line between two cameras. The time-of-flight solution needs an advanced electronic processor to determine the time difference between the light firing time and the reflected light receiving time. The structure light solution is getting popular recently since it does not need large base line between two cameras, and it does not need advanced electronic processor.
However, the size of a conventional structure light module is still relatively large for consumer electronic applications. Accordingly, a novel structure light module having small size is demanded.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention.